Vibrational and electrochemical studies of pectin-a candidate towards environmental friendly lithium-ion battery development.

Pectin polymers are considered for lithium-ion battery electrodes. To understand the performance of pectin as an applied buffer layer, the electrical, magnetic, and optical properties of pectin films are investigated. This work describes a methodology for creating pectin films, including both pristine pectin and Fe-doped pectin, which are optically translucent, and explores their potential for lithium-ion battery application.

Flow-induced "waltzing" red blood cells: Microstructural reorganization and the corresponding rheological response.

We investigate flow-induced structural organization in a dilute suspension of tumbling red blood cells (RBCs) under confined shear flow. For small Reynolds ( = 0.1) and capillary numbers (), with fully coupled hydrodynamic interaction (HI) and without interparticle adhesion, we find that HI between the biconcave discoid particles prompts the formation of layered RBC chains and synchronized rotating RBC pairs, referred here as "waltzing doublets.

Probing the Stoichiometry Dependence of Enzyme-Catalyzed Junction Zone Network Formation in Aiyu Pectin Gel via a Reaction Kinetics Model.

We investigate the enzymatic self-catalyzed gelation process in aiyu gel, a natural ion crosslinked polysaccharide gel. The gelation process depends on the concentration ratio () of the crosslinking calcium ions and all galacturonic acid binding sites. The physical gel network formation relies on the assembly of calcium-polysaccharide crosslink bonds.

Analysis of Gas Nanoclusters in Water Using All-Atom Molecular Dynamics.

The Young-Laplace equation suggests that nanosized gas clusters would dissolve under the effects of perturbation. The fact that nanobubbles are observed raises questions as to the mechanism underlying their stability. In the current study, we used all-atom molecular dynamics simulations to investigate the gas-water interfacial properties of gas clusters.

Effects of Gas Adsorption and Surface Conditions on Interfacial Nanobubbles.

Gas aggregation and formation of interfacial nanobubbles (INBs) provide challenges and opportunities in the operation of micro-/nanofluidic devices. In the current study, we used molecular dynamics(MD) simulations to investigate the effects of hydrophobicity and various homogeneous surface conditions on gas aggregation and INB stability with a series of 3D argon-water-solid and water-solid systems. Among various signatures of surface hydrophobicity, the potential of mean force (PMF) minima exhibited the strongest correlation with the water molecular orientation at the liquid-solid interface, compared to the depletion layer width and the droplet contact angle.

Rich phase transitions in strongly confined polymer-nanoparticle mixtures: Nematic ordering, crystallization, and liquid-liquid phase separation.

We investigate the rich phase behavior of strongly confined semi-flexible (SFC) polymer-nanoparticle (NP) systems using the graphics processing unit accelerated Langevin dynamics simulation. Hard nanoparticles (HNP) that repel each other and ideal nanoparticles (INP) that do not interact with the same species are used as model additives to a strongly confined semiflexible polymer fluid. Both types of NPs exclude the monomer beads in the same way, but they have qualitatively different effects on the SFC isotropic-nematic (I-N) transition.

Shear-induced non-monotonic viscosity dependence for model red blood cell suspensions in microvessels.

The cell-free layer thickness of an aggregating red blood cell (RBC) suspension in a rectangular microchannel is investigated by hybrid fluid-particle numerical modeling. Several factors affect the suspension viscosity, cell-free layer thickness, and the cell aggregate distribution. These include the hematocrit, vessel size, red cell stiffness, aggregation interaction, and shear rate.

Investigating Interfacial Effects on Surface Nanobubbles without Pinning Using Molecular Dynamics Simulation.

We investigated how the stability of aqueous argon surface nanobubbles on hydrophobic surfaces depends on gas adsorption, solid-gas interaction energy, and the bulk gas concentration using molecular dynamics simulation with the SPC/E water solvent. We observed stable surface nanobubbles without surface pinning sites for longer than 160 ns, contrary to previous findings using monoatomic Lennard-Jones solvent. In addition, the hydrophobicity of a substrate has an effect to reduce the requirement degree of oversaturation on water bulk.

STAT3-coordinated migration facilitates the dissemination of diffuse large B-cell lymphomas.

The motile characteristics and mechanisms that drive the dissemination of diffuse large B-cell lymphoma (DLBCL) are elusive. Here, we show that DLBCL initiates dissemination through activating STAT3-mediated amoeboid migration. Mechanistically, STAT3 activates RHOH transcription, which competes with the RhoGDP dissociation inhibitor RhoGDIγ to activate RhoA.

Investigation of nematic to smectic phase transition and dynamical properties of strongly confined semiflexible polymers using Langevin dynamics.

We investigated the nematic to smectic phase transition for strongly confined semiflexible polymer solutions in slit-like confinements using GPU-accelerated Langevin dynamics. We characterized the phase transitions from the nematic to smectic phases for semi-flexible polymer solutions as the polymer density increased. The dependence for the lyotropic nematic to smectic transition can be collapsed by scaling exponents between 0.

Emerging Roles of Air Gases in Lipid Bilayers.

Recent studies indicate that changing the physical properties of lipid bilayers may profoundly change the function of membrane proteins. Here, the effects of dissolved nitrogen and oxygen molecules on the mechanical properties and stability of lipid bilayers are investigated using differential confocal microscopy, atomic force microscopy, and molecular dynamics simulations. All experiments evidence the presence of dissolved air gas in lipid bilayers prepared without gas control.

Significantly increased low shear rate viscosity, blood elastic modulus, and RBC aggregation in adults following cardiac surgery.

Open heart surgeries are common for treating ischemic and heart valve disease. During cardiac surgery, cardiopulmonary bypass (CPB) can temporarily take over the function of heart and lungs. However, elevated red blood cell (RBC) aggregation may lead to the common side-effects such as microinfarction.

Electrofluidic Circuit-Based Microfluidic Viscometer for Analysis of Newtonian and Non-Newtonian Liquids under Different Temperatures.

This paper reports a microfluidic viscometer with an integrated pressure sensor based on electrofluidic circuits, which are electrical circuits constructed by ionic liquid-filled microfluidic channels. The electrofluidic circuit provides a pressure-sensing scheme with great long-term and thermal stability. The viscosity of the tested fluidic sample is estimated by its flow resistance, which is a function of pressure drop, flow rate, and the geometry of the microfluidic channel.

Confinement, curvature, and attractive interaction effects on polymer surface adsorption.

We investigate the conformation and dynamics of a semi-flexible polymer near an attractive plane or a cylindrical post using Langevin dynamics. We characterize the transition from the desorbed to absorbed state and quantify how absorption depends on the attraction interaction, polymer molecular weight, polymer flexibility, intra-polymer interaction, and micro-confinement. We find that the critical point of adsorption for ideal flexible polymers only weakly depends on confinement.

Modeling shear-induced particle ordering and deformation in a dense soft particle suspension.

We apply the lattice Boltzmann method and the bead-spring network model of deformable particles (DPs) to study shear-induced particle ordering and deformation and the corresponding rheological behavior for dense DP suspensions confined in a narrow gap under steady external shear. The particle configuration is characterized with small-angle scattering intensity, the real-space 2D local order parameter, and the particle shape factors including deformation, stretching and tilt angles. We investigate how particle ordering and deformation vary with the particle volume fraction ϕ (=0.

Abnormal polymer transport in crowded attractive micropost arrays.

We investigate polymer diffusion in a quasi-two-dimensional environment decorated with attractive cylindrical posts using Langevin dynamics simulation. We find that the polymer diffusivity has non-monotonic dependence on the post array density. This diffusive behavior strongly depends on the adsorption-desorption transition and the critical adsorption strength ε.

Clusters of circulating tumor cells traverse capillary-sized vessels.

Multicellular aggregates of circulating tumor cells (CTC clusters) are potent initiators of distant organ metastasis. However, it is currently assumed that CTC clusters are too large to pass through narrow vessels to reach these organs. Here, we present evidence that challenges this assumption through the use of microfluidic devices designed to mimic human capillary constrictions and CTC clusters obtained from patient and cancer cell origins.

Entropic attraction: Polymer compaction and expansion induced by nano-particles in confinement.

We investigated nanoparticle (NP)-induced coil-to-globule transition of a semi-flexible polymer in a confined suspension of ideal NP using Langevin dynamics. DNA molecules are often found to be highly compact, bound with oppositely charged proteins in a crowded environment within cells and viruses. Recent studies found that high concentration of electrostatically neutral NP also condenses DNA due to entropically induced depletion attraction between DNA segments.

Conformation-dependent translocation of a star polymer through a nanochannel.

The translocation process of star polymers through a nanochannel is investigated by dissipative particle dynamics simulations. The translocation process is strongly influenced by the star arm arrangement as the polymer enters the channel, and a scaling relation between the translocation time [Formula: see text] and the total number of beads N tot is obtained. Qualitative agreements are found with predictions of the nucleation and growth model for linear block co-polymer translocation.

Nanoslit Confined DNA at Low Ionic Strengths.

We present nanoslit confined DNA conformations at very low ionic strengths and a theory to explain most measurements for single DNA molecule size under strong nanoslit confinement. Very low ionic strength conditions not only increase the DNA persistence length dramatically, but also cause DNA molecules to swell to the extent that the effective diameter of DNA becomes larger than the nanoslit height. By accounting for these effects, our results and theory provide a reasonable clue for a current controversy regarding the dependence of the DNA conformation on slit height (), persistence length (), and effective diameter ().

Erratum: "Electro-entropic excluded volume effects on DNA looping and relaxation in nanochannels" [Biomicrofluidics 7, 054119 (2013)].

[This corrects the article on p. 054119 in vol. 7.

Electro-entropic excluded volume effects on DNA looping and relaxation in nanochannels.

We investigate the fluctuation-relaxation dynamics of entropically restricted DNA molecules in square nanochannels ranging from 0.09 to 19.9 times the persistence length.

Entropy-driven single molecule tug-of-war of DNA at micro-nanofluidic interfaces.

Entropy-driven polymer dynamics at the nanoscale is fundamentally important in biological systems but the dependence of the entropic force on the nanoconfinement remains elusive. Here, we established an entropy-driven single molecule tug-of-war (TOW) at two micro-nanofluidic interfaces bridged by a nanoslit, performed the force analysis from a modified wormlike chain in the TOW scenario and the entropic recoiling process, and determined the associated scalings on the nanoconfinement. Our results provide a direct experimental evidence that the entropic forces in these two regimes, though unequal, are essentially constant at defined slit heights, irrespective of the slit lengths and the DNA segments within.